Today, motor vehicles include various electronic control units mounted in the motor vehicle. The control units may control various systems and/or subsystems within the motor vehicle. For example, a control unit may control an engine, a transmission, a brake or a steering mechanism. These control units are typically coupled to a variety of sensors and/or actuators. Depending on the vehicle, the control units within a motor vehicle may implement various different communication protocols. In addition, many of these control units may operate at different voltage levels and may transmit in differential or single-ended modes.
In addition, both the U.S. Environmental Protection Agency (EPA) and the CARB have also issued regulations that require standardized programming tools to be used for all vehicle manufactures. This regulation includes requirements for reprogramming emission-related control modules in vehicles for all manufactures by the after market repair industry. In response to the requirements, the SAE has set forth a recommended practice for pass-thru vehicle programming (SAE J2534-1) to satisfy the intent of the EPA and the CARB.
An OBD II compliant vehicle can include one or more of three communication protocols; SAE J1850 variable pulse width modulation (VPWM), SAE J1850 pulse width modulation (PWM), and ISO 9141-2. Most current General Motors (GM) cars and light trucks implement the J1850 VPWM communication protocol. A majority of current Chrysler, European and Asian Import vehicles implement the ISO 9141-2 communication protocol. Most current Ford vehicles implement the J1850 PWM communication protocol. However, motor vehicles that are not OBD II compliant have implemented various other communication protocols. In addition, OBD II compliant motor vehicles may include motor vehicle control units that implement other non-OBD II compliant communication protocols.
In a typical motor vehicle when a fault occurs, that is monitored by a control unit, that fault is logged within memory. In a typical situation, a malfunction indicator light (MIL) is also lit to inform a driver of the motor vehicle that a problem exists. In attempting to trouble-shoot an indicated fault, a service technician typically connects a diagnostic tool to a diagnostic connector provided on the motor vehicle. A typical diagnostic tool includes a microcontroller and an interface circuitry to convert the electronic signals supplied by a control unit in the motor vehicle to a signal that is readily useable by the microcontroller of the diagnostic tool.
Certain diagnostic tools have included multiple hard-wired communication circuits that allowed the diagnostic tool to interpret multiple protocols from different control units. Other diagnostic tools have included a field programmable gate array (FPGA). The FPGA allowed a diagnostic technician to download different images into the FPGA, such that the FPGA could accommodate different communication protocols. In this case, the FPGA served as a communication interface between one of the motor vehicle control units and the microcontroller located in the diagnostic tool. New FPGA models have been made to allow the processor to communicate with different controls units without requiring the FPGAs to be reprogrammed. They serve as a communication interface between the motor vehicle control units and the microcontroller/processor located in the diagnostic tool. However, many motor vehicles include multiple control units that implement different communication protocols within the same motor vehicle. Nonetheless, the microcontroller/processor of the currently available FPGA can only communicate with one control unit at a time due to the different communication protocols. Accordingly, it is necessary to have a new diagnostic tool that can allow the microcontroller/processor to simultaneously communicate with a number of control units that have different communication protocols.